Environmental
Assessment¾ Depleted Uranium (DU) Armor Penetrating Munitions for the GAU-8 Automatic
Cannon, Development and Operational Test and Evaluation, Office of the Air Force
Surgeon General (AF/SGPA), April 1975.

Davitt,
Richard P., A Comparison of the Advantages and Disadvantages of Depleted Uranium and
Tungsten Alloy as Penetrator Materials, Tank Ammo Section Report No. 107, Dover, NJ:
US Army Armament Research and Development Command, June 1980.

Elder,
J.C. and M.C. Tinkle, Oxidation of Depleted Uranium Penetrators and Aerosol Dispersal
at High Temperatures, LA-8610-MS, Los Alamos, NM: Los Alamos Scientific Laboratory of
the University of California, December 1980.

Life
Cycle Environmental Assessment for the Cartridge, 120mm: APFSDS-T, XM829, Picatinny
Arsenal, NJ: US Army Armament Research, Development and Engineering Center, Close Combat
Armament Center, December 12, 1988.

Life
Cycle Environmental Assessment for the Cartridge, 105mm: APFSDS-T, XM900E1, Picatinny
Arsenal, NJ: US Army Armament Research, Development and Engineering Center, Close Combat
Armament Center, August 21, 1991.

Life
Cycle Environmental Assessment for the Cartridge, 120mm: APFSDS-T, XM829A2, Picatinny
Arsenal, NJ: US Army Production Base Modernization Activity, February 2, 1994.

This report concluded that
expended DU munitions' major ecological hazard would be chemical toxicity rather than
radiation. Because DU munitions are composed of alloys, the DU's mobility decreases
substantially compared to natural uranium. However, the report stated that the chemical
toxicity of expended DU to terrestrial ecosystems could not be ignored and must be
seriously considered.

One of the first scientific
studies to evaluate the nature of particles generated during hard impact testing;
researchers conducted five tests firing U-2/3 percent Ti 30mm (272 gram) penetrators
against armor plate. The researchers analyzed the resulting respirable aerosol particle
sizes with four eight-stage Anderson impactors. Two impactors collected samples from the
chamber in front of the target and two impactors from the rear (i.e., exit) chamber.
Researchers dismantled the 0.25m3 entrance and 0.27 m3 exit chambers
after each shot and collected and processed the residual fragments through a US Standard
Sieve Series with sieve fractions of <53, 53 to 105, 105 to 500, 500 to 2000, 2000 to
5660 and >5660 µm fragments. The effective cutoff diameters for the 8 impactor stages
were 11, 7, 4.7, 3.3, 2.1, 1.1, 0.65, and 0.43 µm.

Researchers fired five shots.
However, the first shot's data and half the data from the second and third shots were
lost due to overloading of the impactor stages. Even though all tests were conducted at
0° obliquity and velocities that varied by only 2 percent between the minimum and
maximum, the test results varied widely. The percentage of the penetrator recovered in the
entrance chamber varied by over a hundredfold whereas the range in the exit chamber varied
by only sixfold. Typically, about 80 percent of the total sample weight and uranium
content occurred in the large fragment fraction from the exit chamber. The uranium content
of the large fragments in the entrance chamber varied widely, perhaps indicating the
entrance chamber armor plate disintegrated. The report stated the mass distribution was
1:4 between the entrance and exit chambers "indicating that much of the DU penetrator
pierced the armor plate unfragmented." "Compounded samples of the six size
fractions from the exit chamber contained nearly three times the uranium found in similar
aggregate samples from the entrance chamber."

This was the US Air Force's
GAU-8 Ammunition Program Environmental Assessment, covering manufacturing, transportation,
storage, use, and disposal. The Report's conclusion was a finding of "no significant
environmental impact."

On August 26, 1975, the Los
Alamos Laboratory under contract to the US Air Force Armament Laboratory, Eglin AFB, FL
tested the new 30mm armor piercing GAU-8 ammunition containing a DU core to establish its
hazard classification. In addition to "fragment pattern scoring," testers
conducted air sampling to evaluate the potential for creating airborne DU. The bonfire
cook-off set off 180 live GAU-8 rounds. The test plan did not include measuring aerosol
size characteristics and mass concentrations.

Analysis of the air sampling data
concluded nothing beyond the obvious fact that DU aerosol was released. Of the 180 rounds,
179 (the exception being a shell base) remained within 400 feet of the bonfire. The DU
penetrators lost a good deal of mass in the bonfire -- about 30 percent of the
penetrators lost visually detectable amounts of DU. The remaining 70 percent escaped the
high temperatures that normally turn DU into aerosol and ash. The report states,
"Almost total dispersion of several penetrators to aerosol and ash illustrated the
probable fate of any penetrator remaining in a high temperature region." In other
words, in fires, the potential for DU aerosol dispersion is greater than in other
scenarios.

This was one of the initial
efforts to evaluate the ecological effects of releasing depleted uranium during explosives
tests at selected sites at Eglin AFB, Florida, and Los Alamos Scientific Laboratory
(LASL), Los Alamos, New Mexico. At Eglin, researchers collected samples adjacent to the
target gun butts and 60, 120, 180, and 240 feet from the gun butts. At each location, a
sample was collected from the top 5 centimeters (cm) of ground and from a depth of 5 to 10
cm. The gun butt samples averaged 800 ppm of uranium in the upper 5 cm interval,
approximately 30 times more than in the 5 to 10 cm interval. The report stated this
indicated "modest vertical movement of depleted uranium into the soil." Samples
collected 60 feet from the gun butts indicated levels of 20 ppm and 2 ppm in the 0 to 5
and 5 to 10 cm intervals. Samples collected beyond 20 feet indicated near background
levels of uranium or about 2.3± 10 µg/g (ppm).

Researchers also monitored
residues at two Los Alamos explosives testing sites. Levels at the E-F Site averaged 2499
ppm uranium (natural and depleted uranium) in the upper 5 cm level and 1600 ppm in the 5
to 10 cm levels. Levels in the second test area were approximately 2.5 and 0.6 percent of
the E-F site values. The report stated, "Important concentration differences with
depth and distance from the detonation points were ascribed to the different explosive
test designs peculiar to each area."

The report also cited average
vegetative levels of 320 ppm of uranium at the E-F site in November 1974 versus 125 ppm in
June 1975. By comparison, the levels in small mammals trapped in November contained a
maximum of 210 ppm in the GI tract, 24 ppm in the pelt, and 4 ppm in the remaining carcass
compared to 110, 50 and 2 ppm in similar samples in June 1975. The study stated that their
data emphasize "the importance of resuspension of respirable particles in the upper
few millimeters of soil as a contamination mechanism in several components of the
ecosystem."

The report stated, "Soil
analysis indicated that relatively large fragments as well as fine particulates from
uranium explosive tests corrode readily and then migrate into the soil at variable rates.
Weathering is apparently faster in the humid environment and porous soil at EAFB than at
LASL."

The study concluded typical field
conditions met the protective standards for radiation contained in 10 CFR 20.105 with
these provisos: "(1) Occupancy of any area 100 cm from any accessible surface of
stored CNU-309/E containers by non-occupationally exposed personnel does not exceed a
total of 1,000 hours per year, and that (2) the PGU-14/B cartridge is in a case when
handled (if the cartridge is handled directly, the total contact time with the projectile
surface should not exceed 180 hours per calendar quarter)."

This early study attempted to
examine gross morphological characteristics of particulates formed during hard impacts of
DU penetrators. Although the Air Force performed this test, researchers used the
Army's 105mm tank round, not the Air Force's 30mm DU penetrator. Some of the
report's key conclusions include:

Scanning electron microscopy
revealed airborne particulates were primarily spherical, the surfaces of which were highly
convoluted. Particles were at times comprised of partially overlapping, concave plates,
formed as a result of polyfocal solidification. Extreme fracturing, particularly along the
convoluted folds and plate lines, accounted for the apparent fragility associated with
airborne particles of the rugose type. Under normal weathering conditions such particles
could be expected to break up rapidly, thereby contributing to an increase in the total
number of respirable-size particles.

Particle disintegration would
be further accelerated by the hollow nature of many of the spheres. Hollow particles,
which are frequently thin-walled or perforated, are extremely vulnerable to weathering and
thus subject to rapid deterioration.

The elemental composition of
individual particles was qualitatively determined by non-destructive x-ray spectroscopy.
Airborne particles were comprised primarily of alloyed uranium and iron. Although the
ratio of the two metals varied considerably among particles, the fact that alloying did
occur is consistent with violent interaction between penetrator and target at impact.

An unexpected phenomenon was
the formation of ultrafine particles less than 0.1 µm in diameter. These particles,
generally observed adhering to the surfaces of larger particles, presumably were formed as
a result of the extreme temperature achieved and the highly reactive nature of pyrophoric
depleted uranium. These ultrafine particles exhibited an extreme tendency to coalesce,
probably due to spontaneous diffusion charging. This coalescing tendency of particles,
which were originally below the respirable size-range, is especially significant since it
resulted in the formation of abundant agglomerates that fell within the respirable range.

Particles isolated from soil
samples near the target area, in addition to uranium and iron, frequently contained
appreciable amounts of silicon, aluminum, and/or tungsten. Fusion with both silicon and
aluminum had been anticipated as a result of interaction with sand and clays within the
soil. The presence of tungsten was due to contamination of the target site from previous
test firings of high-density penetrators employing that material.

Results show that appreciable
quantities of respirable-size particles are released during use of these projectiles.
Although particles are initially formed over an extremely broad range, eventual weathering
of large particles together with coalescence of ultrafine particles combine to increase
the potential total number of particulates within the respirable range.

In this test an A-10 aircraft
attacked two combat-loaded individual Soviet T-62 tanks in five missions totaling seven
passes; technicians rehabilitated the two vehicles after each pass. The aircraft were
seldom higher than 200 feet in altitude; firings were initiated between 2768 and 4402 feet
and terminated at ranges of 1587 to 3055 feet at dive angles of 1.8 to 4.4°. The bursts
ranged from 120 to 165 rounds.

Altogether 93 DU rounds struck
the tanks during the seven passes, including no impacts on one pass. The ratio of impacts
to rounds fired was 0.10. Of the 93 impacts, 17 penetrated the armored envelopes for a
ratio of perforations to impacts of 0.18. The report noted many of the side or rear
impacts that did not penetrate the armor nonetheless extensively damaged the tanks'
exterior suspension components, whereas all the rounds that hit the tanks' front
caused minimal damage. These results reinforced the strategy of attacking tanks from the
side or rear to optimize damage potential.

The Joint Technical Coordinating
Group for Munitions Effectiveness Working Group on Depleted Uranium Munitions recommended
this as one of three studies in its initial 1974 DU environmental assessment. This study
focused on the health physics problems associated with assembling, storing, and using
105mm APFSDS-T XM774 ammunition. The report concluded, "Radiation levels associated
with the XM774 ammunition are extremely low. The photon emissions measured did not exceed
a maximum whole-body or critical organ exposure of 0.26 mR/hr. Even if personnel were
exposed for long periods to the highest levels of radiation measured, it is doubtful that
their exposure would reach 25 percent of the maximum permissible occupational dose listed
in Title 10 of the Code of Federal Regulations, Part 20."

This was the last of three
studies the Joint Technical Coordinating Group for Munitions Effectiveness (JTCG/ME)
recommended in the late 1970s; the other two were "Radiological and Toxicological
Assessment of an External Heat (Burn) Test of the 105mm Cartridge, APFSDS-T, XM774"
and "Radiation Dose Rate Measurements Associated with the Use and Storage of XM774
Ammunition." The purpose of this test was to obtain the data necessary to evaluate
the potential risk to human health from exposure to airborne DU. The data included:

Size distribution of airborne DU.

Quantity of airborne DU.

Dispersion of airborne DU from the target
vicinity.

Amount of DU deposited on the ground.

Solubility of airborne DU compounds in lung fluid.

Oxide forms of airborne and fallout DU.

The study extensively assessed
total and respirable DU levels above and downwind of the targets, fallout and fragment
deposition around the target, and cloud volume, estimated by analyzing high-speed movies
of the smoke generated by the penetrator impact. Although technical problems occurred
during the test (e.g., filter overload, etc.), the researchers drew these conclusions:

Each test firing generated
approximately 2.4 kg of airborne DU.

Approximately
75 percent of the airborne DU was U3O8 and 25 percent was UO2.

Immediately
after the test, about 50 percent of the airborne DU was respirable, of which 43 percent
was dissolved in simulated lung fluid within seven days. After seven days the remaining DU
was essentially insoluble.

While
respirable-sized airborne particles predominantly were U3O8, they
also included iron and traces of tungsten, aluminum, and silicon compounds.

The
report stated, "Measurement of airborne DU in the target vicinity (within 20 ft.)
after a test firing showed that personnel involved in routinely changing targets could be
exposed to concentrations exceeding recommended maximums. This may have resulted in part
from mechanical resuspension of DU from the soil or other surfaces."

The researchers encountered
numerous problems in sampling for total particulates, which contributed to their
conclusion the average fraction of the penetrator that aerosolized was 70 percent. These
problems included:

The particulate samplers became
clogged and the flow rates dropped to zero, requiring researchers to estimate the sampling
time;

The
number of fallout trays near the target was inadequate to determine the amount of DU
deposited on the ground; and

Researchers
could not fully evaluate the cloud volumes because of inadequate films of the cloud.

Despite the technical problems
encountered during the test, 70 percent is frequently cited as the average amount of
penetrator aerosolized during hard impact.

Battelle first released this
report to the US Army in 1979 but the project office decided not to publish it then. Due
to the current interest in the historical Depleted Uranium testing program and the
uncertainty associated with the frequently-cited 70 percent aerosolization figure, in June
1999 Battelle decided to publish this report. This information is extracted from
Battelle's summary:

This report is a follow-up to the
hard target impact testing of the M774 and takes advantage of the field experience and
difficulties faced in that 1977 test to improve test conditions and sample collection.
This second test, conducted in 1978 at Ford's Farm within Maryland's Aberdeen
Proving Ground, was more successful in characterizing the impact cloud plumes, as well as
measuring time-integrated concentrations (TIC) with time since impact and particle size
distributions. Uncertainties so prominent in the M774 report are considerably reduced in
this M735E1 evaluation.

In this test, the 105-mm M735E1
cartridges were fired at a series of three armor plate targets located about 200 meters
away. The impact and penetration of the projectiles caused a shower of fragments and
considerable airborne particulates. This projectile assembly contained a 2.2-kg DU core.
Specific objectives of the test included investigating:

TICs at specific near-target locations;

Concentration in the target accessway for the
first 15 minutes after the shot was fired;

Concentrations near the target 10 minutes after
the shot was fired taken over a 5-minute interval;

Concentrations near the target 15 minutes after
the shot taken over a half-hour interval;

Growth rate of the airborne cloud;

Fraction of the penetrator that was aerosolized;
and

Size distribution of the airborne DU particulates.

During this test, the uranium
concentration was reduced faster under wet surface conditions. Additionally, it appeared
that the concentration of the cloud was probably uniform and representative at 2 second
post-shot. Using cloud volume and airborne mass, the airborne fraction of the penetrators
could be calculated.

The overall results of the test
are as follows:

The aerosolized fraction of the M735E1 penetrator
from target impact ranged from 17 percent to 28 percent.

The airborne uranium concentrations in the target
accessway were above the maximum permissible concentration in air (MPCa)[535]for occupational
exposure. The MPCa was calculated to be 278 ug/m3 based on the 10
CFR 20 requirements in 1977, for the first 5 minutes post-shot. The continued airborne
level of DU remained elevated at least for 15 minutes when the surface was dry. It was
reduced below the MPC within 15 minutes when the surface was wet.

At 4 to 5 meters from the target accessway, the
uranium concentrations were below MPCa within 10 minutes and remained so
irrespective of surface wetness or of work activity in or near the target accessway after
the 15 minutes post-test mark.

The rate of decrease in DU concentration in and
near the target accessway was greater under wet surface conditions than dry ones.

The wetness of the ground surface had no
discernable impact on the airborne cloud volume or the total mass of material made
airborne immediately after a test firing.

Although there were two separate measurements of
particle size in measurements of the target accessway, the authors believed the MMAED of
2.1 µm of airborne uranium with four-stage high-volume cascade impactors (operated at 20
cfm) was probably a better measure of particle size than the 5.8-µm MMAED value
calculated using the low-volume eight-stage cascade impactors flow rates (operated at 1
cfm [4.9 ´ 10-4 m3/sec]).

Video documentation (high-speed
motion pictures), used to estimate cloud volume as a function of time, and meteorological
measurements of wind speed and direction conducted by site personnel assisted in
interpreting data.

Aerosols from Hard Target Impact

Airborne Fraction

Particle Size Distribution

Post-Shot Concentrations

17 to 28%

2.1-µm
MMAED with hi-vol monitor; 5.8-µm MMAED with low-vol monitor

Above
MPC (278 µg/m3) for 5 min at target and remained elevated for 15 min with dry
surface, less with wet surface

This report provides an excellent
history of the logic behind the Army's decision to use DU as a kinetic energy,
armored-piercing munition. DU's final selection over tungsten was based on several
reasons, including the lower initial cost of the penetrator itself and its better overall
performance. DU and tungsten were rated even for "producibility." Tungsten had
the advantage for safety, environmental concerns, and deployment.

This early test evaluated the
consequences of exposing DU penetrators to various thermal conditions ranging from 500° C
to 1,000° C in different atmospheres for two to four hours. The tests' general
conclusions were:

DU aerosols with
respirable-sized particles are produced when penetrators are exposed to temperatures above
500° C for one-half hour or more.

Exposing
the penetrators to sustained fires, forced drafts and temperature cycling enhanced the
production of oxide and aerosol.

Since the
penetrators themselves are not flammable, complete oxidation required adequate fuel and a
fire longer than four hours.

The Nuclear Regulatory Commission
(NRC) required this early documentation to support indoor, confined testing of 105 and
120mm kinetic energy DU rounds. NRC initially approved the test firing of 10 rounds to
verify the integrity of the test facility; then it approved firing 20 DU penetrators to
characterize the aerosol generated by their impact with an armor target. The study results
contradicted Battelle's previous study for the XM774, which indicated up to 70
percent of the DU penetrator aerosolized on impact. In this study, approximately 3 percent
of the penetrator aerosolized 2 to 3 minutes after impact, and accounting for error, it
was highly unlikely more than 10 percent aerosolized. The test data were consistent with
previous test data for small-caliber ammunition. For the aerosolized particulates, the
mass mean diameter was 1.6 micrometers and approximately 70 percent were fewer than 7
micrometers, considered the upper range of DU's respirable particulates. The study
raised many questions about the nature of aerosols generated by hard-impact testing of DU
penetrators.

The purpose of this test was to
determine the behavior of the XM829 cartridge when subjected to detonation of an adjacent
XM829 cartridge and a sustained hot fire. The test concluded that detonating an XM829
cartridge in one container would not cause the immediate detonation of XM829 cartridges in
adjacent cartridges. But if a fire starts and continues to burn, adjacent cartridges may
ignite, scattering debris up to 40 feet. A mass analysis for the two experiments conducted
under this project showed at least 80 percent of the cartridge's mass was recovered
in the 1982 test and 100 percent in the 1983 test. No DU contamination was detected in
samples from the sand taken from ground zero. Analysis of the filters from seven
high-volume air samplers also indicated airborne uranium levels remained at natural
background levels. The report noted, "Great care was taken during this time to
prevent the residue from being scattered by winds and that under different conditions
these values could vary." An analysis of the respirator canisters also revealed no
measurable DU levels.

This project's purposes were
twofold: to characterize DU oxide samples' particle size, morphology, and lung
solubility from 120mm M829 DU rounds exposed to an external heat test and to conduct a
literature search on "uranium oxidation rates, the characteristics of oxides
generated during the fire, the airborne release as a result of the fire, and the
radiological/toxicological hazards from inhaled uranium oxides."

The test results indicated a
maximum of 0.6 percent by weight of the DU oxide generated was in the respirable range
(i.e., less than 10 m m Aerodynamic Equivalent Diameter) and the respirable fraction of
the oxide was insoluble (i.e., 96.5 percent had not dissolved within 60 days). The study
concluded DU oxides formed during burning should be classified as insoluble (Class
Ydissolution half-times in the lung of more than 100 days).

The Project Manager, M1A1 Abrams
Tank System, US Army Tank and Automotive Command, supported this test. The tank was loaded
with 40 M829 120mm rounds to evaluate crew radiation exposure levels. "Preliminary
results of the radiation exposures to M1A1 tank crews were well within the Nuclear
Regulatory Guidelines for the general population and there was no undue radiation hazard
when the tank was fully loaded with M829 rounds."

This overview of DU describes its
relationship to natural uranium, its commercial and military applications, and its
long-term effects on man and the environment. The Army wrote this report to fulfill the
relevant background information requirements for its documentation, detailed in Army
Regulation (AR) 200-2.

The report described the
Army's computer modeling, which was created to determine whether to impose an
exclusion zone around an accident site, where to locate a boundary, if any, and whether
the potential effects further downwind would be significant or trivial based on the
incident's characteristics, the actual munitions involved, and the munitions'
packaging.

This followed up the Hazard
Classification Test summarized in PNL 4459 (Report 16 above), which was conducted with a
wooden shipping container. This follow-up test was conducted to evaluate a new PA-116
metal shipping container. The report's conclusions were:

Igniting a round in a metal shipping container by
way of an external source did not cause the detonation of the entire package contents.

Igniting one round surrounded by other rounds did
not cause sympathetic detonation of the other rounds.

The individual explosions blew cartridge and
shipping container fragments into the air. The penetrators were recovered within 20 feet
of the fire. Most of the fragments fell within 200 feet. Two fragments were recovered
between 300 to 600 feet from the fire.

Four of the 12 penetrators from the fire test
showed evidence of oxidation. One penetrator core had oxidized almost completely to oxide
powder.

The test also revealed these
radiological aspects:

About 9.5 percent of the total DU in the 12 cores
was converted to oxide during the fire.

The oxide was predominantly U3O8.

The fraction of generated oxide aerodynamically
small enough to be suspended in air and carried by the wind was 0.002 to 0.006 (0.2
percent to 0.6 percent).

The fraction of generated oxide small enough to be
inhaled was about 0.0007 (0.07 percent).

The solubility of the DU oxide in simulated lung
fluid indicated 96 percent was essentially insoluble, four percent dissolved in the fluid
within 10 days.

During the test, winds were relatively calm.
"Air monitors (detection limit of 1m g DU) set up to intercept downwind DU aerosol
detected no DU on their filters and tended to confirm that there was no significant
airborne DU oxide."

The study concluded, "The
minute quantity of oxide that was of respirable size and the calm winds limited the
downwind disposal and posed no biological hazard to cleanup crews or others in the
area."

A follow-up study to a 1983 study
evaluating potential health problems when shipping and storing M829 cartridges in wooden
containers, this assessment evaluated radiation levels when packaging the M829 in a
metallic container. Study results include the following:

The M829 components effectively shield out the
predominant nonpenetrating radiation emitted from the bare penetrator; the 1.0-MeV photons
resulting from the decay of the 234mPa can penetrate both the projectile
components and metal container.

The radiation levels emanating from the assembled
M829 cartridge are no different from the 1983 study, and the slightly higher radiation
measurements at the package surface are due to the reduced distance between the penetrator
and the outer package surfaces.

The radiation levels associated with the M829
ammunition do not present a significant potential hazard to personnel handling and storing
the ammunition.

Measured with field-use-exposure-rate instruments,
the radiation levels at the single shipping container's surface do not exceed 0.5
mR/hr; and the M829 shipping package satisfies all other 49 Code of Federal Regulations
173.421 and 173.42 criteria. The package therefore qualifies for shipment as
"excepted from specification package, shipping paper and certification, marking and
labeling requirements;" however, the inner or outer package must bear the word
"Radioactive."

The ammunition prepared for shipment must be
certified as acceptable for transportation by having a notice enclosed in or on the
package, included with the packing list, or otherwise forwarded with the package. This
notice must include the name of the co-signer and the statement, "This package
conforms to the conditions and limitations specified in 49 CFR 173.424 for articles
manufactured from depleted uranium, UN 2909."

This was the initial
Environmental Assessment (EA) for the M829 armor piercing round, which replaced the XM827
(the American analog of the German DM 13), the initial APFSDS-T round. The program
included developing and testing four rounds: Target Practice (M831), High Explosive
(M830), Armor Piercing (XM827), and Target Practice (M865). The EA incorporates all
previous supporting studies on the M829 round (e.g., the radiological and hazard
classification of the metal and wooden shipping containers). The EA's conclusion was
a "Finding of No Significant Impact" for the M829's design, production,
test and evaluation, deployment, and demilitarization.

In this study the XM900E1 round
was packaged in a PA-117 steel container. The report's conclusions are as follows:

The components of the XM900E1 effectively shield
out the predominant non-penetrating radiation emitted from the bare penetrator and
significantly reduce the majority of the penetrating radiation. The 1.0 MeV photons
resulting from the decay of 234mPa can penetrate both the components of the
projectile and the metal canister but are somewhat reduced.

Radiation levels associated with the XM900E1
ammunition do not present a significant potential hazard to personnel handling and storing
the ammunition.

Radiation levels at the surface of the single
shipping package, measured with field-exposure-rate instruments, do not exceed 0.5 mR/hr
and all other criteria specified by the US Department of Transportation (DOT) in 49 CFR
173.21 and 49 CFR 173.424 are satisfied by the XM900E1 shipping package.

This study, one of several
conducted on 105mm M774 ammunition, addresses only one objective -- the amount of DU
aerosol and fallout around and downwind of the armor-bustle target. "Very little of
the depleted uranium of the M774 penetrator left the immediate target area as an
aerosol." The highest value -- regardless of the wind conditions -- was so low
more than 1,400 such tests would have to be fired in a week before tolerance limits would
begin to be reached. While the occupational Threshold Limit Value was exceeded when the
cloud passed over the samplers, the time-weighted-average exposure for a 40-hour work week
was only 0.07 percent of the occupational threshold limit.

This report discusses factors affecting the
conversion of DU metal to oxide, the subsequent influences on uranium's leaching and
mobility through surface water and groundwater pathways, and growing plants'
absorption of uranium. The Army undertook this project to attempt to understand
uranium's environmental impact.